It has recently been asserted that legislative moves to consider plants as ethical subjects are philosophically foolish because plants lack autonomy. While by no means the sole basis or driving criterion for moral behavior, it is possible to directly challenge skeptical attitudes by constructing a human-plant ethics centered on fundamental notions of autonomy. Autonomous beings are agents who rule themselves, principally for their own purposes. A considerable body of evidence in the plant sciences is increasingly recognizing the capacity of plants to assess, perceive, and act on their environment. The primary purpose of their doing so is to generate the conditions for their own flourishing. With these plant purposes in mind, it is evidentially inappropriate to treat plants purely as instruments. In this age of environmental crisis, knowledge of plant intelligence and autonomy opens up a new debate on respecting and promoting the well-being of the plants that make life on Earth possible